This invention relates to an arrangement for sealing structural members, particularly in the case of turbo-engines. A structural member is divided along a first plane into segments, which can be moved relative to one another. The structural member is movable in a second plane, which is angularly offset with respect to the first plane. Projections of the segments engage sealingly in a groove of an additional structural member. Expansion gaps are arranged between abutting edges of the segments and are sealed off longitudinally and transversely with respect to the course of the gap via sealing plates.
In the case of turbo-engines, particularly gas turbine engines, guiding baffles of turbines are divided into segments along their circumference, while expansion gaps are left, in order to control differential expansions in the circumferential direction which occur with respect to nonsteady operating conditions. In addition, such guiding baffles, by way of the shroud segments, are arranged radially inside or radially outside on at least one point by means of projections or webs which extend along the circumference. In this manner, the guiding baffles can be moved in the radial direction on grooves of the turbine housing in order to compensate different radial relative expansions with respect to the housing. As a result of the above-mentioned arrangement, thermally caused tensions which occur at the guiding baffle can be reduced.
In the interest of low process losses, the expansion gaps between the shroud segments are sealed off by sealing plates which movably engage in mutual open recesses on the abutting edges. The sealing plates, in view of the course of the expansion gaps and of the projections or webs, abut on one another while they are mutually offset with respect to one another in an axial/radial manner.
In the case of this arrangement, the web or the projection also forms a sealing surface at least with respect to a groove surface. Furthermore, it is a prerequisite that the expansion gaps on the side facing away from the hot gas flow in the guiding baffle, together with the sealing plates, are acted upon by sealing air taken out of the compressor and possibly used also for the cooling of the turbine housing. Because of the movable arrangement of the sealing plates, sealing air circulations against the hot gas flow are virtually unavoidable. In the case of this arrangement, a leakage flow proportion of sealing air, which locally is comparatively large, will occur at the point of the expansion gap, i.e., between the sealing plate, which is in each case arranged radially at the level of the web or the projection, and the corresponding opposite sealing surface of the groove on the projection.
The indicated problems analogously also occur in the case of other combinations of structural members, of which one structural member is segmented in the longitudinal direction.
There is therefore needed a sealing arrangement of the above-described type which, particularly in view of the mentioned critical point on the respective expansion gap of the segmented structural member, creates an optimal sealing which is connected with extremely low process losses.
According to the present invention, this need is met by an arrangement for sealing structural members, particularly in the case of turbo-engines. A structural member is divided along a first plane into segments, which can be moved relative to one another. The structural member is movable in a second plane, which is angularly offset with respect to the first plane. Projections of the segments engage sealingly in a groove of an additional structural member. Expansion gaps are arranged between abutting edges of the segments and are sealed off longitudinally and transversely with respect to the course of the gap via sealing plates. Each expansion gap is sealed off between a sealing plate, which is arranged transversely with respect to the course of the gap, and an opposite surface of the groove acting as a sealing surface, via a V-shaped insert. The V-shaped insert is actuated by a local pressure difference; is arranged in the direction of the groove base using free legs which spread open; is expanded via two legs in the direction of the opposite sealing surface of the groove; is disposed via the expansion in a sealing manner on corresponding oblique abutting surfaces of the segments; and covers the expansion gap via a base wall sloping in the direction of its sealing end face on the groove between both legs.
In this manner, a highly effective sealing of the points of the expansion gaps that are indicated to be critical is achieved In other words, it is achieved that that particular leakage flow of the sealing fluid which consists, for example, of supplied high-pressure air, is drastically reduced. That is the result of the local overflowing of the sealing plate which is arranged radially or approximately in parallel with respect to the locally bent course of the projections.
The present invention is based on a sufficient pressure difference between the fluid pressure (sealing air), which exists at the groove, and the fluid pressure, particularly the hot gas pressure, which exists downstream of the V-shaped insert and is static, for example. In the case of this arrangement, an insert with three sealing surfaces is obtained. These three sealing surfaces are the rear end face disposed on one side of the groove, and the two sealing surfaces which are constructed laterally on the legs. The two sealing surfaces constructed laterally on the legs follow a V-course and are also sloped as a result of the widening of the insert in the direction of the one groove side. With this additional slope, the insert is pressed by way of the pressure difference with its rear end face in a sealing manner against the one side of the groove. As a result of the V-shape, the insert forms sliding surfaces in order to compensate manufacturing tolerances and temperature-caused changes of the expansion gaps. The flattened and correspondingly sloped center or base wall between the two legs of the insert forms relatively large pressure surfaces at the expansion gap which are acted upon by differential pressure. At the mentioned point of the expansion gap, the insert can easily be mounted from the outside. In this case, the local point of the gap has a correspondingly preprofiled recess for the insert between adjacent abutting edges of the segments. In view of the generally relatively small gap width, the insert therefore forms comparatively large structural member surfaces which are effective for the differential pressure.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.